Organic compositions stabilized with 3, 5-dialkyl-4-hydroxybenzyl amine



United States Patent C) 3,208,859 ORGANIC COMPOSITIONS STABILIZED WITH 3,5- DIALKYL-4-HYDROXYBENZYL AMINE Thomas H. Cotfield, Heidelberg, Germany, assignor to Ethyl Corporation, New York, N.Y., a corporation of Virginia No Drawing. Filed Feb. 23, 1960, Ser. No. 10,023 The portion of the term of the patent subsequent to July 10, 1979, has been disclaimed 14 Claims. (Cl. 99-163) This invention relates to novel chemical compounds having utility in the chemical arts.

In particular, this invention relates to novel 3,5-dialkyl- 4-hydroxybenzyl amines. which are eminently suited for use as antioxidants.

Among the objects of this invention is that of providing new chemical compounds useful for the above and other purposes. Another object is to provide methods of preparing these new chemical compounds. Another object of this invention is to provide organic material stabilized against oxidative deterioration. A further object is to provide hydrocarbon oil normally tending to deteriorate in the presence of oxygen containing these new compounds in amount suflicient to inhibit this deterioration. Another object is to provide lubricating oil and greases normally tending to deteriorate in the presence of oxygen containing, in amount suflicient to inhibit such deterioration, a small antioxidant quantity of novel and highly effective antioxidants. Still another object is to provide turbine and other industrial oils stabilized against oxidative deterioration by the presence therein of a small antioxidant quantity of novel and highly effective antioxidants. Other objects will be apparent from the ensuing description.

The above and other objects of this invention are accomplished by providing as new compositions of matter 3,5- dialkyl-4-hydroxybenzyl amines having the general formula:

wherein R is an alkyl group containing from 1 to 12 carbon atoms, R is an alkyl group containing from 3 to 12 carbon atoms which is branched on the alpha carbon atom, R is selected from the group consisting of alkyl, cycloalkyl, aralkyl, aryl, and alkaryl and and R is selected from the group consisting of hydrogen, alkyl, cycloalkyl, aralkyl, aryl .and alkaryl. In the above compounds it is preferable that the hydrocarbon radicals of the groups designated above as R and R contain the following ranges of carbon atoms: alkyl, 1 to, 12; cycloalkyl, 5 to 6; aralkyl, 7 to 11; aryl, 6 to and alkaryl, 7 to 15.

A preferred embodiment of this invention relates to 3,5-dialkyl-4-hydroxybenzyl amines in which at least one of R and R is an alkyl group as above-defined. The compounds of this embodiment are more effective antioxidants for oxygen-sensitive oils than are the remainder of the compounds of this invention.

A particularly preferred embodiment of this invention is 3,5-dialkyl-4-hydroxybenzyl amines in which at least one of R and R is an alkyl group as above-defined and R and R are both tertiary alkyl groups containing from 4 to 12 carbon atoms. These latter compounds possess outstanding effectiveness as antioxidants for a wide variety of oxygen-sensitive oils, such as lubricating oil, transformer oil, turbine oil, gear oil and the like.

The most particularly preferred embodiment of this invention is compounds described above in which R and R are tertiary butyl groups, and in which at least one of R and R is a lower alkyl group, that is, an alkyl group containing from 1 to 6 carbon atoms.

Typical compounds of this invention include: N-cyclohexyl-N- 3 -methyl-5 -isopropyl-4-hydroxybenzyl) amine,

N-benzyl-N- 3,5 -diisopropyl-4-hydroxybenzyl) amine,

N-b enzyl-N- 3 ,'5 -d-i-tert-butyl-4-hydroxyb enzyl amine,

N-phenyl-N- (3 -methyl-5 (2- octyl) -4-hydroxybenzyl) amine,

N-( 3,5 -xylyl) -N- 3 ,5 -di-tert-amyl-4-hydroxybenzyl) amine,

N e yclohexyl-N,N-bis- (3 ,5 -diiso pro pyl-4 -hydroxybenzyl amine,

N- (p-butylbenzyl) -N,N-bis.- 3 ,5 ,di-tert-butyl-4- hydroxybenzyDamine,

N-benzyl-N,N-bis- 3-methyla5- 1, 1,3,3-tetrarnethylb utyl -4hydroxyb enzyl amine,

N- a-naphthyl) -N,N-bis- 3,5adiisopropyl-4hydroxybenzyl) amine,

N- p-tolyl -N,N-bis- 3 ,5 -d-i- (2-dodecyl -4- hydroxybenzyl).amine,

N,N-di-(phenyl) -N- 3,5-di- (Z-hexyl) -4-hydroxybenzyl) amine,

N-phenyl-N- (p-tolyl) (-3,5-di- (Z-Iamyl) -4-hydroxyb enzyl) amine,

N- p-octylphen yl) -N- 3-ethyl-5-tert-butyl-4-hydroxybenzyl)amine, and the like.

The preferred embodiment of this invention as above described is illustrated by such compounds as N-methyl-N- 3,5 -diisopropyl-4-hydroxyhenzyl amine, N-octyl-N- 3methyl-S-tert-butyl-4-hydroxybenzyl) amine,

N- 2-dodecyl) -N- 3,5 -di- (Z-hexyl -4-hydroxybenzyl) amine,

N,N-diethyl-N- 3-isopropyl-S-tert-butyl-4-hydroxybenzyl) amine,

N,N-di-butyl-N- 3 ,5 -diisopropyl-4-hydroxybenzyl) amine,

N-methyl-N-ethyl-N- 3 ,S-di- (2-octyl -4-hydroxybenzyl) amine,

N-sec-butyl-N-dodecyl-N-(3,5-diisopropyl-4-hydroxybenzyl)-amine,

N-propyl-N,N-bis- 3-methyl-5-tert-butyl-4-hydroxybenzyl) amine,

N- (sec-.amyl) -N,N-bis- 3,5 -di-sec-butyl-4-hydroxybenzyl) amine,

N-decyl-N,N-bis- 3 -ethyl-5 3 -decyl -4-hyd roxybenzyl) amine, and the like. The particularly preferred embodiment of this invention is illustrated by such compounds as N-heptyl-N- 3 ,5 -di-tert-buty1-4-hydroxybenzyl amine, N-isopropyl-N- 3 ,5 -di-tert-amyl-4-hydroxybenzyl amine, N-nonyl-N-(3-tert-butyl-5-tert-amyl-4-hydroxybenzyl) amine; N,N-diisobutyl-N-(3,5-di-tert-amyl-4-hydroxybenzyl) amine;

N,N-dioctyl-N- (3 ,5 -di- 1,1,3 ,3-tetramethylbutyl) -4- hydroxybenzyl) amine;

N-propyl-N-amyl-N- 3 ,5 -di-( 1,1,2,2-tetramethylpropyl)-- 4-hydroxybenzyl amine;

N-methyl-N,N-bis(3,5-ditert-amyl-4-hydroxybenzyl) amine;

N-hepty1-N,N-bis- 3,5-di-tert-amyl-4-hydroxybenzyl) amine;

N-undecyl-N,N-bis- 3 -tert-butyl-5-tert-amyl-4-hydroxybenzyl)amine, and the like.

The most particularly preferred embodiment of this invention comprises such compounds as N-methyl-N- 3 ,5 -di-tert-butyl-4-hydroxybenzyl) amine;

N-ethyl-N- 3 ,5 -di-tert-butyl-4-hydroxybenzyl) amine;

N-butyl-N- 3 ,5 -ditert-butyl-4-hydroxybenzyl) amine,

N-isohexyl-N- 3 ,5 -di-tert-b utyl-4-hydroxyb enzyl) amine;

N,N-dimethyl-N- 3,5 -di-tert-butyl-4-hydroxybenzy1) amine;

N,N-di-propyl-N- 3 ,5 -di-tert-butyl-4-hydroxybenzyl) amine;

N-methyl-N-ethyl-N- 3 ,5 -di-tert-butyl4-hydroxybenzyl) amine;

N-ethyl-N,N-bis- 3 ,5 -di-tert-butyl-4-hydroxybenzyl) amine;

N-butyl-N,N-bis- (3,5 -di-tert-butyi-4-hydroxybenzyl) amine;

N-tert-amyl-N,N-bis- 3,5-di-tert-butyl-4-hydroxybenzyl) amine, and the like.

The compounds of this invention are white or pale yellow crystalline solids and are soluble in various organic solvents and in gasolines, diesel fuels, hydrocarbon oils and the like. These compounds are further characterized by being relatively stable, easily cryst-allizable materials.

The compounds of this invention are prepared by reacting a 2,6-dialkyl phenol in which one of the alkyl groups contains from 3 to 12 carbon atoms and is branched on the alpha carbon atom and the other alkyl group contains from 1 to 12 carbon atoms; formaldehyde; and a primary or secondary amine in which the hydrocarbon portion thereof is in conformity with the groups designated hereinabove as R and R In conducting this process a monohydric alcohol containing from 1 to 6 carbon atoms is preferably used as the reaction solvent. The reaction temperature is in the order of about 20 to about 100 C. It is preferred to conduct the process of this invention within the range of about 50 to 90 C.

In conducting this process the relative proportions of the three reactants is varied depending upon the particular type of 3,5-dialkyl-4-hydroxybenzyl amine being prepared. Thus, when preparing the N,N-di-hydrocarbon substituted-N-(3,5-dialkyl-4-hydroxybenzyl)amines of this invention, one mole of formaldehyde and one mole of dihydrocarbon substituted amine'i.e., secondary amineare employed per mole of appropriate 2,6-dialkyl phenol. When preparing N-hydrocarbon-N,N-bis-(3,5-dialky1-4- hydroxybenzyDamines of this invention, one mole of formaldehye and one-half of a mole of mono-hydrocarbon substituted amine-Le, primary amineare reacted er mole of appropriately substituted 2,6-dialky1 phenol used. When preparing the compounds of this invention which contain one hydrogen atom and one hydrocarbon group on the nitrogen atom, one mole of a formaldehyde and a large excess of primary amine are employed per mole of 2,6-dialkyl phenol used. This substantial excess of primary amine is in the order of about 8 to about 10 moles per mole of phenol used. This particular reaction is conducted in a large amount of mono-hydric alcohol solvent in order to achieve dilution of the reactants.

Thus, a facet of this invent-ion is a process of preparing 3,5-dialkyl-4-hydroxybenzyl amines which comprises reacting a 2,6-dialkyl phenol in which one of the alkyl groups contains from 3 to 12 carbon atoms and is branched on its alpha carbon atom and the other alkyl group contains from 1 to 12 carbon atoms; formaldehyde; and an amine having the general formula wherein R is selected from the group consisting of alkyl containing from 1 to 12 carbon atoms, cycloalkyl containing from to 6 carbon atoms, aralkyl containing from 7 to 11 carbon atoms, aryl containing from 6 to carbon atoms and alkaryl containing from 7 to 15 carbon atoms and R is selected from the group consisting of hydrogen and R as just defined.

The compounds of this invention and the methods for their preparation are illustrated by the following specific examples wherein all parts and percentages are by weight.

EXAMPLE 1 In a reaction vessel equipped with stirring means, reflux means, thermometer and reagent introducing means were placed 89 parts of 2,6-diisopropyl phenol, 248 parts of percent aqueous dimethylamine solution and 500 parts of ethanol. To this solution was added 75 parts of 37 percent formalin solution at room temperature and the mixture refluxed for 4 hours at 83 C. The reaction mixture was then hydrolyzed with excess cold water and the solid product filtered off to give a 98 percent yield of N,N- dimethyl N (3,5 diisopropyl-4-hydroxybenzyl)amine, melting at -87 C. The analysis calculated for C H NO: 76.5 percent carbon, 10.7 percent hydrogen and 5.98 percent nitrogen. Found: 77 percent carbon, 10.6 percent hydrogen, and 5.89 percent nitrogen.

EXAMPLE 2 In a reaction vessel equipped as described above, 103 parts of 2,6-di-tert-butyl phenol, 248 parts of 25 percent aqueous dimethyl amine solution and 75 parts of 37 percent formalin solution were reacted at 75 C. in 500 parts of ethanol for 3 hours. The reaction mixture was then poured into excess cold water and the solid which formed filtered off to give a 98 percent yield of N,N-dimethyl-N- (3,5-di-tert-butyl-4-hydroxybenzyl)amine, melting point 92 C. The analysis calculated for C H NO: carbon 77.51 percent, hydrogen 11.1 percent. Found: carbon 77.60 percent, hydrogen 11.0 percent.

EXAMPLE 3 Into the reaction equipment described in Example 1 are introduced 178 parts of 2,6-diisopropyl phenol, 38 parts of 40 percent aqueous methyl amine solution, 84 parts of a 37 percent aqueous solution of formalin and 500 parts of ethanol. These materials are then heated to a temperature of 70 C. On completion of the reaction, the mixture is poured into an excess of cold water and the solid materials which form are filtered off to give N-methyl-N,N-bis (3,5 diisopropyl 4 hydroxybenzyl) amine.

EXAMPLE 5 In the reaction vessel of Example 1 are placed 159 parts of 2,6-di-(l,1,3,3-tetramethylbutyl)phenol, 45 parts of 37 percent aqueous formalin solution, 29 parts of 40 percent aqueous ethyl amine solution and 400 parts of methanol. This mixture is heated at 70 C. for 4 hours. On cooling and partially evaporating the solvent, N-ethyl- N,N-bis-(3,5-di-(1,1,3,3 tetramethylbutyl) 4 hydroxybenzy1)amine precipitates and is filtered olf.

EXAMPLE 6 In the reaction vessel of Example 1 are placed 15 parts of 2-methyl-6-isopropyl phenol, 8.4 parts of 37 percent aqueous formalin soltuion, 77 parts of 40 percent aqueous methyl amine and 400 parts of ethanol. This mixture is stirred at 30 C. for 4 hours. The solvent is removed at reduced pressure with 25 mm. of mercury and the product crystallized from the residue. The product is N-methyl-N-(3-methyl 5 isopropyl 4 hydroxybenzyl) amine.

EXAMPLE 7 Using 500 parts of ethanol as reaction solvent, N,N-dibenzyl-N-(S-isopropyl 5 tert-butyl 4 hydroxybenzyl) amine is prepared by reacting 97 parts of 2-isopropyl-6- tert-butyl phenol, 45 parts of 37 percent aqueous formalin solution and 98 parts of dibenzyl amine. The reaction is carried out at 70 C. for 4 hours. The product is recovered by partially evaporating the solvent and crystallizing the residual liquor.

EXAMPLE 9 Using the reaction equipment described in Example 1, 220 parts of 2-methyl-6-(1,1,3,3-tetramethylbutyl)phenol, 84 parts of 37 percent aqueous formalin solution and 113 parts of methyl(cyclohexyl)amine are reacted at a temperature of 73 C. for 5 hours using 800 parts of isopropanol as solvent. The reaction mixture is poured into cold water and the product crystallized from the insoluble organic portion. The product is N-methyl-N-cyclohexyl- N-[3-methyl-5-(l,l,3,3 tetramethylbutyl) 4 hydroxybenzyl] amine.

EXAMPLE 10 In the reaction vessel described in Example 1 are placed 89 parts of 2,6-di-tert-butyl phenol, parts of 37 percent aqueous formalin solution, 65 parts of aniline hydrochloride and 800 parts of ethanol. This mixture is stirred at 70 C. for 12 hours and poured into dilute sodium bicarbonate solution. N-phenyl-N,N-bis-(3,5-di-tert-butyl-4- hydroxybenzyl)amine is filtered off as a crystalline solid.

EXAMPLE 12 At a temperature of 65 C., 208 parts of 2,6-di-tertbutyl phenol, 85 parts of 37 percent aqueous formalin solution, and 130 parts of dibutyl amine are reacted in 700 parts of ethanol. After 4 hours, the reaction mixture is poured into cold Water and the N,N-butyl-N-(3,5-ditert-butyl-4-hydroxybenzyl)amine filtered off as a white solid.

EXAMPLE 13 Using 700 parts of ethanol as reaction solvent, 215 parts of 2,6-di-(2-dodecyl) phenol, 45 parts of aqueous 37 percent formalin solution and 143 parts of N-methyl aniline hydrochloride are heated for 5 hours at 70 C. The reaction mixture is poured into cold water and the N-methyl-N-phenyl-N-(3,5-di-(2-dodecyl) 4 hydroxybenzyl)amine crystallized from the insoluble residues.

EXAMPLE 14 N,N-diphenyl-N-(3-isopropyl-5-tert-butyl 4 hydroxybenzyl)amine is prepared by reacting 97 parts of 2-isopropyl-6-tert-butylphenol, 45 parts of 37 percent aqueous formalin solution, and 103 parts of diphenylamine hydrochloride in 800 milliliters of ethanol solvent. The reaction is carried out at 70 C. for 12 hours and then poured into cold water. The product is crystallized from the insoluble organic portion.

6 EXAMPLE 15 Using 700 parts of ethanol as the solvent, N-methyl-N- [EB-naphthyl-N- (3 ,5 -diisopropyl-4-hydr0xybenzyl) amine is prepared by reacting 89 parts of 2,6-diisopropylphenol, 45 parts of 37 percent aqueous formalin solution and 110 parts of N-rnethyl-B-naphthyl amine hydrochloride. The reaction is carried out at 70 C. for 12 hours and then poured into cold dilute sodium bicarbonate solution. The product is then crystallized from the insoluble organic portion.

EXAMPLE 16 At 65 C., N,N-dodecyl-N-(3,S-di-tert-butyl-4-hydroxy benzyl)amine is prepared by reacting 103 parts of 2,6-ditert-butyl phenol, 45 parts of 37 percent aqueous formalin solution and 176 parts of di-dodecylamine for *6 hours. The reaction solvent used is 600 parts of ethanol. The product is obtained by pouring the reaction mixture into cold water, followed by crystallization of the insoluble organic residues from ligroin.

EXAMPLE 17 N tert butyl N (3,5 di tert butyl 4 hydroxybenzyl)amine is prepared by reacting 21 parts of 2,6-ditert-butyl phenol, 8.4 parts of 37 percent aqueous formalin solution and 146 parts of tert-butyl amine. 1000 parts of ethanol is used as reaction solvent and the temperature is held at 30 C. for 4 hours. .The solvent is evaporated at a pressure of 25 mm. of mercury and the residues poured into cold water. The product is crystallized from the insoluble organic portion.

EXAMPLE 18 21 parts of 2,6-di-tert-butyl phenol, 8.4 parts of 37 per-cent aqueous formalin solution, and parts of 2,6- diethyl aniline hydrochloride are stirred at 30 C. in 500 parts of ethanol for 12 hours. At the end of this time the solvent is evaporated at 30 mm. pressure of mercury and the residues washed with cold water. The product is crystallized from the insoluble organic portion to provide white crystals of N-(2,6-diethylphenyl)-'N-(3,5-ditert, butyl-4-hydroxybenzyl)amine.

It can be seen from the above illustrative examples that the primary or secondary amines used in the reaction can also be used in the form of their hydrohalide salts. This practice is sometimes advantageous.

The 2,6-dialkyl phenols which are employed as starting materials in the preparation of the compounds of this invention can be prepared by alkylating a phenol or an appropriate mono ortho alkyl phenol with an olefinic hydrocarbon in the ,presence of an aluminum phenoxide catalyst.

The compounds of this invention have been found to be outstanding antioxidants in a wide variety of organic compositions. Thus, an embodiment of this invention comprises a novel composition of matter made up of organic material normally tending to undergo oxidative deterioration in the presence of air, oxygen, ozone or other oxidizing atmosphere, containing a small antioxidant quantity, up to 3 percent, of a compound of this invention. A preferred embodiment of this invention comprises the use of 3,5-di-alkyl-4-hydroxybenzyl amines in which at least one of R and R is an alkyl group and one of R and R is a tertiary butyl group, R R R and R, as being defined above.

The compositions of this invention find important utility as antioxidants in a wide variety of oxygen-sensitive materials. Thus, liquid and solid products derived from petroleum crude are found to possess greatly increased stability in use and in storage by the inclusion therein of an antioxidant of this invention. For example, gasoline, jet fuel, kerosene, fuel oil and various waxes have increased oxidative stability when they contain an antioxidant of this invention. Likewise, liquid hydrocarbon fuels which contain organometallic additives such as tetraethyllead and other organometallic compositions which are used as fuel additives attain an appreciably increased oxidative stability by the practice of this invention. Furthermore, such fuels which contain halogen and phosphorus containing scavengers for these organometallic compounds are benefited by the practice of this invention.

The compounds of this invention effectively inhibit oxidation in industrial lubricants of the hydrocarbon type, such as lubricating oil, turbine oil, transformer oil, transmission fluids, glass-annealing oil, gear and machine lubricants, hydraulic lubricants and other industrial oils, grease and the like. As pointed out above, the compounds of this invention as a class are effective antioxidants. In addition to increased storage stability lubricating oils and functional fluids such as automatic transmission and hydraulic fluids, both those derived from naturally occurring hydrocarbon and those synthetically prepared achieve a high degree of resistance to oxidation during use at elevated temperatures by the practice of this invention. It has been found that lubricating oils may be employed at extremely high temperatures without undergoing oxidative degradation when protected by an antioxidant of this invention. Furthermore, the compounds of the various embodiments of this invention substantially differ in effectiveness from one embodiment to another. For example, the compounds of the preferred class of this invention are more effective antioxidants than the compounds of this invention as a class. Still more effective are the particularly preferred compounds of this invention. As brought out by the experimental results described in connection With Table I below, the compounds of the most particularly preferred embodiment of thi invention possess still greater effectiveness as antioxidants. In short, the compounds of the most particularly preferred embodiment of this invention are superlative antioxidants.

The addition of small quantities of the compound of this invention to lubricating greases prepared from both natural and synthetic oils by the addition of metallic soaps greatly increase their resistance to oxidation. Furthermore, the organic soaps used in the preparation of lubricating greases are themselves stabilized by the practice of this invention.

Organometallic compositions such as tetraethyllead and tetraethyllead antiknock fluids containing halohydrocarbon scavengers, dyes and which may contain various soap compounds and other organometallic additives are stabilized against deterioration during storage by the addition thereto of an antioxidant quantity of the compositions of this invention.

The compounds of this invention are also extremely effective stabilizers and antioxidants for elastomers including high molecular weight unsaturated hydrocarbon polymers, both those derived from naturally occurring sources and those synthetically prepared. Thus, natural rubbers and synthetic rubbers both raw and vulcanized, including oil extended rubbers, are greatly benefited by the practice of this invention. Examples of the synthetic rubbers protected by the practice of this invention include such synthetics as polybutadiene, methyl rubber, polybutad-iene rubber, butyl rubber, SB-R rubber (GR-S rubber), GR-N rubber, piperylene rubber, dimethyl butadiene rubber, polybutene rubber, isobutylene styrene copolymers, polyisobutylene, polystyrene and the like.

In addition, saturated hydrocarbon synthetic polymers are greatly enhanced against oxidative deterioration by the practice of this invention. Such polymers are in general those derived from the polymerization of a hydrocarbon monoolefin having up to about carbon atoms. Thus, polymers and copolymers derived from ethylene, propylene, butene, isobutylene, pentene, 2-methyl-3-butene and the like are within the scope of this invention.

The compounds of this invention are also useful in protecting petroleum waxparaffin wax and micro-crystalline Waxagainst oxidative deterioration. The compounds of this invention also find use in the stabilization of edible fats and oils of animal or vegetable origin which tend to become rancid especially during long periods of storage because of oxidative deterioration. Typical representatives of these edible fats and oils are linseed oil, cod liver oil, castor oil, soybean oil, rapeseed oil, coconut oil, olive oil, palm oil, corn oil, sesame oil, peanut oil, babassu oil, butter, fat, lard, beef tallow, and the like. In addition, fish oilssuch as cod liver oilas well as various foods containing or prepared in animal fats which tend to deteriorate are protected by this invention. These include, for example, potato chips, fried fish, donuts, crackers, and various types of pastry such as cakes and cookies. Furthermore, fat fortified animal feeds and fish meals used as animal feeds are greatly benefited by the practice of this invention. Not only are these compositions protected against oxidative deterioration but the inclusion of a composition of this invention in such materials inhibits the degradation of vitamins, A, D and E and certan of the B complex vitamins. Examples of compositions containing oils derived from vegetable sources which are benefited by the practice of this invention include castor oil, soy bean oil, rapeseed oil, coconut oil, olive oil, palm oil, corn oil, sesame oil, peanut oil, babassu oil, citrus oils, cotton seed oil and various compositions containing these including peanut butter, peanuts and other whole nuts, salad dressings, margarine and other vegetable shortenings.

The compositions of this invention are also outstanding antioxidants for various organic compounds and polymeric materials including polystyrene, polyvinylchloride, polyvinyl acetate, various epoxide resins and polyester resins and polymers including the alkyds.

The compounds of this invention may also be used as anti-oxidants for gasolines containing lead alkyl antiknock agents, such as tetraethyllead; concentrated formul ations of tetraalkyllead compounds, such as pure tetraethyllead or tetraethyllead admixed with organic halogen scavengers, oxygen-sensitive diesel fuels, domestic heating oils, bunker and residual fuel oils, asphalt, and other organic material normally susceptible of oxidative deterioration.

The amounts of the compounds of this invention employed in the materials to be stabilized are dependent both upon the nature of the material itself and the oxidative conditions to be encountered. Generally speaking, amounts in the order of about 0.001 to about 3 percent by weight of the material to be protected are satisfactory. In some cases such as where the antioxidant is employed in an article normally subjected to severe oxidizing conditions, somewhat higher concentrations are useful.

The compounds of this invention are also useful as additives to functional fluids and automatic transmission fluids. The primary constituent of a functional fluid as a refined mineral lubricating oil having carefully selected minimum viscosity of 49 Saybolt Universal seconds (SUS) at 210 F. and a maximum viscosity of 7,000 SUS at 0 F., generally a distillate oil, lighter than an SAE 10 motor oil. The oil usually amounts to between about 73.5 to about 97.5 percent by Weight of the finished fluid. Preferably, the base oil is selected from a paraffin base distillate such as a Pennsylvania crude.

The fluids usually contain compounds which are characterized by containing one or more organic components which may be alkyl, aryl, alkaryl or aralkyl groups that are bonded to one or more metal atoms through coupling groups such as sulfonate, hydroxyl, carboxyl and mercaptan. The metal atoms may be aluminum, calcium, lithium, barium, strontium, and magnesium. The organic components contain oil solubilizing groups such as high molecular weight straight or branched chain paraflins, aromatic or naphthenic rings, or contain a halogen. These metal compounds are present in the compounded fluid in a concentration range of between about 0.1 to

about percent by weight. These compounds include alkaline-earth metal salts of phenyl-substituted long chain fatty acids, alkaline-earth metal salts of the oapryl or octyl esters of salicylic acid, the alkaline-earth metal salts of petroleum sulfonic acids, the alkaline-earth metal salts of alkyl-substituted phenol sulfides, the salts of aluminum or the alkaline-earth metals with cetyl phenol, and the metal salts of wax-substituted phenol derivatives. Another class of additives are the :so-oalled overbased phenates and sulfonates, which can be prepared by reaction between an alkyl phenol or alkyl phenol sulfide and an alkaline-earth metal oxide or hydroxide at an elevated temperature. The overbased phenate formed from the reaction contains up to two or three times as much metal as the normal phenate.

In addition, functional fluids may contain additional components which improve the properties of the fluid. Typical components and their concentration range in the fluid are as follows:

From about 1 to about 5 percent of an anti-Squawk additive, usually a sulfurized oil, such as sulfurized sperm oil, sulfurized lard, sulfurized vegetable oil, sulfurized glyceride, or a sulfurized ester of fatty acids.

From about 0.05 to about 2 percent of a pour point depressant. Typical types of additives are wax-substituted naphthalenes, esters of wax-substituted phenol, polymerized unsaturated esters and acrylic polymers such as polymerized esters of methacrylic acid.

About 0.005 to about 0.1 percent of a foam inhibitor. Foam inhibitors include fatty acids and fatty acid esters, pine oil, alkyl lactates, higher ethers such as 2-(di-tertamyl phenoxy)ethanol and mixtures of materials such as glycerol and sodium bis(2-ethylhexyl)sulfosuccinate.

From about 0.03 to about 0.1 percent of a rust preventive such as carboxylic acid derivatives including alkylated succinic acid, esters and partial esters of diand polycarboxylic acids, esters and partial esters of hydroxysubstituted diand polycarboxylic acids and alkyl-substituted acids containing at least two carboxylic acid groups joined by nitrogen, oxygen or sulfur esters of acids derived from oxidized petroleum; amine derivatives including hydroxy amines, hydroxy amidines, amine salts of partial esters of phosphorus acids, hydroxy amine salts of oxidized petroleum acids, hydroxy amine salts of fatty acids and long chain alkyl amines; organic sulfonates; long chain alkyl ketones; organic phosphates and phosphites; morpholine derivatives and phosphatides including lecithin and fatty acids.

About 0.1 to about 2 percent of an extreme pressure agent. These include organic compounds containing chlorine, phosphorus and sulfur, such as chlorinated waxes of a P S -terpene reaction product; organic phosphates and phosphites such as for example, tricresylphosphate or a zinc dialkyl dithiophosphate and lead soaps such as lead naphthenate.

From about 0.05 to about 0.2 percent of a metal deac tivator. Such compounds include complex organic nitrogen and sulfur-containing compounds, as for example, amines and sulfides. Also included are such compounds as organic dihydroxyphosphines, trialkyl and triaryl phosphites, certain diamines and soaps containing a metal such as tin, nickel, chromium, thallium or titanium.

From about 1 to about percent of a viscosity index improver such as a polymerized olefin or isoolefin, butylene polymer or alkylated styrene polymer.

The compounds of this invention are outstanding antioxidants for synthetic oils, particularly diester oils of the type described in Industrial and Engineering Chemistry, 39, 48 l-91 (1947). Thus, the compounds of this invention can be used to very effectively stabilize diesters formed by the esterification of straight chain dibasic acids containing from 4 to about 16 carbon atoms with saturated aliphatic monohydric alcohols containing from 1 to about 10 carbon atoms. Generally speaking, diester lubricants that are prepared from branched chain alcohols and which have molecular weights ranging from about 300 to about 600 are especially effective lubricants and are very effectively stabilized by the compounds of this invention. Thus, in the diester lubricant embodiments of this invention, use can be made of oxalates, malonates, succinates, adipates, pimelates, suberates, azelates, sebacates, and the like.

The following examples illustrate the various embodiments of this invention.

EXAMPLE 19 To show the useful properties of the novel compounds of this invention, recourse is had to the Polyveriform Oxidation Stability Test as described in the paper entitled Factors Causing Lubricating Oil Deterioration in Engines (Ind. and Eng. Chem., Anal. Ed. 17, 302 (1945). See also A Bearing Corrosion Test for Lubricating Oils and Its Correlation With Engine Performance (Anal. Chem., 21, 737 (1949). This test effectively evaluates the performance of lubricating oil antioxidants. The test equipment procedure employed and correlations of the results with engine performance are discussed in the first paper above cited. By employing various compounds of this invention in oxygen-sensitive lubricating oil, effective inhibition of oxidative deterioration is achieved.

Comparative tests were conducted using the method and apparatus essentially as described in the publication first above mentioned. One minor modification was that the steel sleeve and copper test piece described in this publication were omitted from the apparatus. In these tests an initially additive-free, V.I. solvent-refined SAE-lO crankcase oil was used. The principal test conditions consisted of passing 70 liters of air per hour through the test oil for a total period of 20 hours While maintaining the oil at a temperature of 280 F. Oxidative deterioration of the oil was further promoted by employing as oxidation catalysts 0.05 percent by weight of ferric oxide (as ferric 2-ethyl hexoate) and 0.10 percent by weight of lead bromide, both of these amounts being based upon the weight of oil employed. Various lubricating oils of this invention were prepared by blending small amounts of typical compounds of this invention with other individual portions of the above lubricating oil. These compositions were then subjected to the above stringent oxidation test. The results of these tests are shown in Table I.

Table 1 EFFECT OF ANTIOXIDANTS ON OXIDATION OF LUBRI- CATING OIL Additive Viscosity Test Additive cone, Acid increase at No. percent No. 10

by wt percent None 5.6 189 N,N-dimethyl- -(3,5-diiso- 1 0 2.9 63

propyl-4-hydroxybenzyl) 3.111116. 3 do 2.0 2.0 51 4 N,N-din1ethyl-N (3,5-di- 1.0 0.27 8

tert-butyl-l-hydroxybenzyl amine. 5 do 2.0 0.18 8 6 N-methyl-N,N-bis-(3,5-di- 1.0 0.17 9

tert-butyl-4-hydroxybenzyl) amine. 7 do 2.0 0.20 12 By referring to the data presented in Table I, it is immediately apparent that the compounds of this invention effectively inhibit oxidative deterioration of lubricating oil. Furthermore, comparison of the results of Tests 4-7 inclusive with those of Tests 2 and 3 show that while the preferred compounds of this invention (in this case N,N dimethyl-N-(3,S-diisopropyl-4-hydroxybenzyl)amine) are very effective antioxidants, the most particularly preferred compounds of this invention (e.g., those used in Tests 4-7) are outstanding. For example, by comparing the results of Test 4 with Test 2 and Test 5 with Test 3, it is obvious that the most particularly preferred compounds of this invention are about ten times as effective as the preferred compounds of this invention. Generally speaking, this difference in effectiveness between the most particularly preferred compounds and the preferred compounds of this invention is in the order of a ten-fold difference.

EXAMPLE To still further demonstrate the preeminence of the most particularly preferred compounds of this invention as antioxidants for use in lubricating oil, another series of comparative tests was conducted. In this instance the test procedure used was essentially as described above with the exception that still more stringent test conditions were employed. These conditions were brought about by conducting the Polyveriform Oxidation Stability Test at a temperature of 300 F. In these tests comparisons were made between a sample of the above-described, additivefree crankcase lubricating oil and a separate portion of this oil with which had been blended 3 percent by weight of N,N-dimethyl-N (3,5-di-tert-butyl-4 hydroxybenzyl) In Table II are shown the results of these tests.

amine.

Table II EFFECT OF ANTIOXIDANTS ON OXIDATION OF LUBRI- OA'IING OIL Viscosity Test No. Additive Neutraliincrease zation No. at 100 F.

percent 1 None 8.8 115 2 N,N-dimetbyl-N-(3,5-di- 0.9 12

tert-butyl-4-hydroxybenzyl) amine.

It is clearly evident from the data shown in Table II that even under more stringent oxidizing conditions, the compounds of the most particularly preferred embodiment of this invention (as represented in this instance by N,N-dimethyl-N-(3,5-di-tert-butyl 4 hydroxybenzyl)amine are outstanding antioxidants for oxygen-sensitive oils.

EXAMPLE 21 The compounds of this invention are particularly effective antioxidants for use in steam turbine oils. This is demonstrated by making use of the standard test procedure of the American Society for Testing Materials bearing ASTM designation D-943-54. According to this test procedure, 300 milliliters of a suitable test oil is placed in contact with 60 milliliters of water and the resulting oil-water system is maintained at a temperature of 95 C. while passing oxygen therethrough at a rate of 3 liters per hour. Oxidation is catalyzed by the use of iron and copper wire. Periodically measurements are made of the acid number of the test oil and failure of an antioxidant is indicated by an acid number in excess of 2.0. It is found that when the various compounds of this invention are added in small antioxidant quantities to steam turbine oils, substantial resistance against oxidative deterioration results.

EXAMPLE 22 The compounds of this invention are very effective antioxidants for grease. The potency of the compounds of this invention in this respect is demonstrated by conducting the Norma Hoffman Grease Oxidation Stability Test, ASTM test procedure D-942-50. It is found that the presence of minor proportions of the compounds of this invention in conventional greases greatly inhibits oxidative deterioration. By way of example an initially antioxidant-free lithium base grease was modified to the extent that it contained 0.5 percent by weight of N,N- dimethyl-N-(3,5-di-tert-butyl-4-hydroxybenzyl)amine and was subjected to the above oxidation stability test. It was found that the presence of N,N-di-methyl-N-(3,5- di-tert-butyl-4-hydroxybenzyl)amine greatly retarded oxygen absorption by the grease. Thus, after maintaining this grease composition in the oxygen bomb for 376 hours under the standard test conditions, the oxygen bomb pressure had been reduced from 110 psi. to 104 p.s.i. This represents an extremely small diminution of oxygen pressure in the light of the severe test conditions employed and is indicative of a negligible amount of oxygen absorption.

The following examples are illustrative of various specific embodiments of this invention. The physical characteristics of the illustrative oils used in Examples 23-28 are shown in Table III.

Table III PROPERTIES OF REPRESENTATIVE PETROLEUM HYDROCARBON OILS Oil: A B O D E F Gravity at 60 API 30. 3 30. 5 28. 8 31. 1 20. 5 31.0 Viscosity, Saybolt:

Seconds at 100 F 178. 8 373. 8 309. 8 169.0 249. 4 335. 4

Seconds at 210 F 52. 0 58. 4 63. 8 51. 5 45. 7 68. 4 Viscosity index 154. 2 107 4 141 0 157. 8 35.8 144. 4 Pour point 30 +10 20 15 0 Flash point 410 465 365 385 Sulfur, percent 0.2 0.3 0.3 0.3 0. 3 0. 1

EXAMPLE 23 To 100,000 parts of Oil A is added with stirring 12 parts (0.012 percent) of N,N dimethyl N (3,5 ditert-butyl-4-hydroxybenzyl)amine. The resulting oil is found to possess improved resistance to oxidative deterioration.

EXAMPLE 24 To 100,000 parts of Oil B is added 2000 parts (2 percent) of N-methyl-N,N-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)amine. On agitating this mixture, a homogeneous solution results and the resulting oil composition possesses enhanced oxidation resistance.

EXAMPLE 25 With 100,000 parts of Oil C is blended 50 parts (0.05 percent) of N,N-di-dodecyl-N- (3,5-di-tert-butyl-4-hydroxybenzyl)amine. The resulting oil possesses enhanced resistance against oxidative deterioration.

EXAMPLE 26 To 100,000 parts of Oil D is added 100 parts (0.1 percent) of N,N-dipropyl-N-(3-methyl-5-tert-octyl-4-hydroxybenzyl)amine. The resulting oil is found to possess enhanced resistance against oxidative deterioration.

EXAMPLE 27 With 100,000 parts of Oil E is blended 5 parts (0.005 percent) of N,N-diphenyl-N-(3-methyl-5-tert-butyl-4-hydroxybenzyl)amine. After mixing the resulting oil possesses enhanced resistance to oxidation.

EXAMPLE 28 To 100,000 parts of Oil F is added 150 parts (0.15 percent) of N-methyl-N,N-bis-(3-methyl-5-tert-butyl-4- hydroxybenzyl)amine. The resulting oil possesses en hanced resistance against oxidative deterioration.

The following examples show typical functional fluids of this invention. The fluids are formed by mixing the ingredients together, while heating the oil to a temperature up to 200 F.

EXAMPLE 29 A fluid of this invention is prepared by blending parts of a conventionally-refined Pennsylvania mineral oil (99 SUS at 100 F.), 2 parts of N,N-dihexyl-N-(3- ethyl-5-tert-amyl-4-hydroxybenzyl)amine, 5 parts of barium petroleum sulfonate, 10 parts of a polyacrylate having a molecular weight of approximately 7,000 dewill be used. Thus, the compounds which have the Si-OSi-- linkages are the siloxanes. Derivatives of silane, SiH in which one or more of the hydrogens in silane are replaced with organic groups are termed the silanes. Silicates and silicate ester compounds are named as oxy derivatives of silane and are called alkoxy or aryloxy silanes.

The silicone oils and greases serving as the base medium for the lubricant compositions of the invention include the polysiloxane oils and greases of the type, polyalkyl-, polyaryl-, polyalkoxy-, and polyaryloxy-, such as polydirnethyl siloxane, polymethylphenyl siloxane, and polymethoxyphenoxy siloxane. Further, included are silicate ester oils, such as tetraalkyloxy and tetraaryloxy silanes of the tetra-Z-ethylhexyl and tetra-p-tert-butylphenyl types, and the silanes. Also included are the halogen-substituted siloxanes, such as the chlorophenylpolysiloxanes.

The polyalkyl, polyaryl, and polyalkyl polyaryl siloxanes are the preferred types of base medium for the silicon-containing lubricant compositions of the invention because of their high oxidative stability over a wide temperature range. The polyalkyl siloxanes, such as the dimethyl polysiloxane, are slightly preferred over the polyaryl, and polyalkyl polyaryl siloxanes because they show the least change in viscosity over a wide temperature range.

Certain halogen containing organic compounds have physical properties which render them particularly well suited as lubricants. Ordinarily, the halogen is either chlorine or fluorine. Typical of the chlorinated organic compounds suitable as lubricants are the chlorodiphenyls, chloronaphthalene, chlorodiphenyl oxides and chlorinated paralfin waxes.

The fluorocarbon lubricants which are enhanced by this invention are linear polymers built up of a recurring unit which is The fluorocarbon oils and greases are very stable chemically and have high thermal stability. These desirable physical properties appear to be closely related to the bond distances occurring in the fluorocarbon polymeric molecule, which may also contain chlorine bonded to carbon.

Polyalkylene glycol lubricants which are benefited by the practice of this invention are ordinarily the reaction product of an aliphatic alcohol with an alkylene oxide. The preferred alkylene oxides are ethylene oxide and propylene oxide. Depending upon the alcohol employed and the molecular weight of the compound, the polyalkyl ene glycol lubricants may be either water insoluble or water soluble. The molecular weights of these polymers may vary from about 400 to over 3,000. In general, the polyalkylene glycol lubricants are characterized by high viscosity indices, low API gravities, low pour points and they have the general formula where n is small integer and depends upon the alkylene oxide employed and x is a large integer from about to about 100 depending upon the molecular weight of the finished lubricant and R represents the hydrocarbon group derived from the particular aliphatic alcohol employed.

Another important class of synthetic materials which are enhanced by the practice of this invention are phosphate esters which are, in general, prepared by the reaction of an organic alcohol with phosphoric acid and have the general formula:

where R, R and R" represent either hydrogen or an organic radical and where at least one of the groups represented by R, R' and R" is an organic radical. Typical of these materials is trycresylphosphate. The phosphate esters are in general characterized by excellent fire resistant properties and high lubricity. However, their thermal stability is such that they are ordinarily unsuited for high temperature applications above about 300 B. Other examples of phosphate esters include: Tris(2-chloro-1-methylethyl)phosphate; tri-n-butyl-phosphate; tris(2-ethylhexyl) phosphate; triphenyl phosphate; tris(p-chlorophenyl)- phosphate; diethyl m-tolyl phosphate; p-chlorophenyl dimethyl phosphate; tris(2-n-butoxyethyl) phosphate; dimethyl m-tolyl phosphate; di-n-propyl m-tolyl phosphate; din-butyl phenyl phosphate; 1,3-butylene fl-chloroisopropyl phosphate; methyl di-m-tolyl phosphate; bis(2-chlorol-methylethyl) m-tolyl phosphate; dimethyl 3,5-xylyl phosphate; 4-chloro-m-tolyl dimethyl phosphate; 2-ethyll-n-propyltrimethylene methyl phosphate; 4-chloro-mtolyl l-methyl trimethylene phosphate; dimethyl n-octyl phosphate, and the like.

The synthetic base greases used in formulating lubricant compositions of the invention are formed by admixing a soap with an oil of any of the types described above. Such soaps are derived from animal or vegetable fats or fatty acids, wool grease; rosin, or petroleum acids. Typical examples are lead oleate, lithium stearate, aluminum tristearate, calcium glycerides, sedium oleate, and the like. In addition, the polyester greases may contain unreacted fat, fatty acids, and alkali; unsaponifiable matter including glycerol and fatty alcohols; rosin or Wool grease; water; and certain additives which may function as modifiers or peptizers.

In formulating the grease compositions of this invention, greases prepared by admixing a lithium soap with the polyester oils are preferred as they have superior oxidative stability as compared with greases formulated with other soaps, such as the sodium, calcium or lead soaps.

In preparing the improved lubricant compositions of this invention, an appropriate quantity of additive is blended with the oil to be stabilized. If desired, preformed concentrated solutions of the stabilizer in the base lubricant can be prepared and then subsequently diluted with additional lubricant to the desired concentration. An advantage of this invention is the fact that the additive compounds are easily and rapidly blended with the base oil and because of the relative low melting point of the stabilizer, there is no danger of separation of the stabilizer from the lubricant under normal use conditions. An additional advantage of this invention is that the benzyl amines are highly compatible with the usual additives that are frequently used to fortify lubricant compositions, such as detergent-dispersants, viscosity index improvers, dyes, anti-rush additives, anti-foaming agents, and the like.

EXAMPLE 32 With 100,000 parts of di-(sec-amyl)sebacate having a viscosity of 210 F. of 33.8 Saybolt Universal seconds (SUS), a viscosity index of 133 and a molecular weight of 342.5 is blended parts (0.1 percent) of N,N- dimethyl N (3,5 di-tert-butyl-4-hydroxybenzyl)amine. The resulting diester lubricant possesses greatly enhanced resistance against oxidative deterioration.

EXAMPLE 33 To 100,000 parts of d-i-(Z-ethylhexyl)sebacate having a viscosity at 210 F. of 37.3 SUS, a viscosity index of 152 and a molecular weight of 426.7 is added 1000 parts (1 percent) of N-benzyl-N,N-bis-(3-methyl-5-tert-butyl-4- hydr0xybenzyl)amine. After mixing, the resultant diester lubricant possesses greatly enhanced oxidation resistance.

13 rived from a fatty alcohol such as cetyl or lauryl alcohol, 0.1 part of a dimethyl silicone polymer anti-foam agent, 2 parts of a dialkyl zinc dithiophosphate and 0.9 part of a dark, viscous liquid having a viscosity of 560 SUS at 210 F., a flash point of 420 F., a pour point of 30 F. and a specific gravity of 60/60 F. of 0.919.

EXAMPLE 30 Another such fluid consists of 95 parts of a solventrefined, light acid-treated, clay-contacted, solvent dewaxed paraflin base distillate mineral oil (110 SUS at 100 F.); 0.1 part of N,N-dipropyl-N-(3,5-diisopropyl-4-hydroxybenzyl)amine; 0.1 part of calcium octyl phenol sulfide; 2 parts of a sulfurized sperm oil having a sulfur content between 10-12 percent, a viscosity of 210 F. of 200 SUS and a pour point of 65 F.; 0.3 part of an ester of an aromatic acid and wax-alkylated phenol having a molecular weight of approximately 450; 2.5 parts of a linear pale color isobutylene polymer of a controlled molecular weight having a viscosity of 3,000 SUS at 210 F., a specific gravity 60/60 F. of 0.875.

EXAMPLE 31 An aromatic transmission fluid is made by mixing 97 percent of an oil blend comprising 59.0 parts of a solvent-extracted, Coastal oil, 40 SUS at 210 F.; 1.0 part of N benzyl-N,N-(3,5-di-tert-butyl-4-hydroxybenzyl) amine; 1.0 part of a barium phenol sulfide containing 2.4 percent barium, 2 percent calcium and 3.5 percent sulfur, having a viscosity of 126 SUS at 210 F., a flash point of 430 F., a pour point of 10 F. and a specific gravity 60/60 F. of 0.97; 1.0 part of sulfurized sperm oil.

Synthetic lubricants which are enhanced by the practice of this invention are, in general, non-hydrocarbon organic compositions; i.e., organic compositions which contain elements other than carbon and hydrogen. Examples of general classes of material which are protected against oxidative deterioration by the inclusion therein of a compound of this invention included diester lubricants, silicones, halogen containing organic compounds including the fluorocarbons; polyalkylene glycol lubricants, and organic phosphates which are suitable as hydraulic fluids and lubricants. Excellent results are obtained with any of these classes of materials; however, it has been found that exceptional oxidative stability upon prolonged storage is imparted to diester lubricants by the practice of this invention. The synthetic diester oils stabilized by the practice of this invention include sebacates, adipates, etc., which find particular use as aircraft instrument oils, hydraulic and damping fluids, and precision bearing lubricants. These diester oils are exceedingly diflicult to stabilize under high temperature conditions. In this invention, use can be made of a wide variety of diester oils of the type described in Industrial and Engineering Chemistry, 39, 484-91 (1947). Thus, use can be made of the diesters formed by the esterification of straight chain dibasic acids containing from 4 to about 16 carbon atoms with saturated aliphatic monohydric alcohols containing from 1 to about 10 carbon atoms. Of these diester oils, it is preferable that the alcohol used in their preparation be a branched chain alcohol because the resultant diesters have very valuable lubricating properties and the inhibitor of this invention very effectively stabilizes these materials against oxidative deterioration. Thus, use can be made of oxalates, malon-ates, succinates, glutarates, adipates, pimelates, suberates, azelates, sebacates, etc.

The diester lubricants used in the lubricant compositions of this invention have the formula:

OOORi \COORZ where R is an aliphatic hydrocarbon radical which may be saturated or unsaturated and has from 2 to 14 carbon atoms and R and R are straight or branched chain alkyl groups. The diesters utilized in the preferred lubricant compositions, include esters of succinic, glutaric, adipic, pimelic, suberic, azelaic and sebacic acid. Typical examples of such esters are d-iisooctyl azelate, di(Z-ethylhexyl) sebacate, di-sec-amyl sebacate, diisooctyl adipate, di(2- ethylhexyl)adipate, di-(Z-ethylhexyl)azelate, di(l-methyl- 4-ethyloctyl) glutarate, diisoamyl adipate, di(2-ethylhexyl) glut-arate, di(2-ethylbutyl)adipate, ditetradecyl seba'cate and di(Z-ethylhexyDpinate.

The preferred diesters are generally prepared by esterifying one mole of a dicarboxylic acid having the general formula: HOOC(CH ),,COOH, where x is an integer of from 2 to 8, with 2 moles of a branched chain alcohol containing at least 4 carbon atoms. Typical are the reactions of succinic, glutaric, adipic, pimelic, suberic or azelaic acid with sec-amyl alcohol, 3-ethyl butane, 2-ethyl hexanol or the branched chain secondary alcohols undecanol or tetradecanol.

The preferred diester lubricant fluids have molecular weights ranging from about 300 to about 600 and freezing and pouring points from about 40 to less than about F. Their flash and fire points range from about 300 F. to about 500 F. and their spontaneous ignition temperatures range from about 100 to about 800 F. The diesters made by reacting a dicarboxylic acid with a branched chain alcohol have been found to have superior viscometric properties as compared with diesters made by reacting dihydric alcohols 'with mon-o-carboxylic acids and thus, diesters prepared by the former method are preferred in formulating the lubricant compositions of this invention.

The diester oils may be formed by the reaction of a polycarboxylic acid with a mono-hydric alcohol, the reaction of a polyhydric alcohol with a mono-carboxylic acid, reaction between a polyhydric alcohol with a polycarboxylic acid, or combinations of the above reactions; for example, reaction of a polycarboxylic acid with a glycol and a monohydric alcohol, reaction of a glycol with a polycarboxylic acid and a mono-carboxylic acid, or the reaction of a glycol, a mono-hydric alcohol, a polycarboxylic acid and a mono-carboxylic acid. The acids may be mono-carboxylic aliphatic acids such as, propionic acid, valeric acid, 2-ethyl enanthic acid, 2,2-dipropyl butyric acid or 3- (2-methylhexyl)valeric acid. They may contain unsaturated linkages, such as, in senecioic acid, sorbic acid, or angelic acid; they may be polycarboxylic aliphatic acids such as succinic acid, glu taric acid, azelaic acid, 5-octene- 1,8-dicarboxylic acid, or 3-hexene-2,3,4-tricarboxylic acid, and they may be aromatic or cycloaliphatic acids, such as cyclohexaneacetic acid, 1,4-cyclopentylenebis acetic acid, phthalic acid, hemimellitic acid, and terephthalic acid.

The alcohols used in preparing the polyester lubricant base materials may be aliphatic mono-hydric alcohols such as propanol, 2-ethyl-3-hexenol, 2-ethyl-4-propyl heptanol, 2-butenol, or 2-methyl propanol. They may be polyhydric aliphatic alcohols, such as 1,6-hexamethylene glycol, 1,10-decamethylene glycol, 2-hexene-1,6-diol, and 1,6-heptylene glycol, and they may be mono or polyhydric alicyclic or aromatic alcohols, such as 4-[m-(2-hydroxyethyl) phenyl] butanol, 3-(3-hydroxyethyl) cyclohex-ane'butanol, p-(hydroxymethyl)phenethyl alcohol, u-methyl-pxylene-a,u'-diol, 1,4-cyclohexane-fl,,8'-diethyl-dimethanol, 2,3-bis(4-hydroxybutyl)benzyl alcohol, 4,4-[3-(3-hydroxyhexyl)-o-phenylene]dibutanol, and 5-[3-(3-hydroxypropyl)cyclopenta-2,4-dienylene]-3-ethyl amyl alcohol.

Another class of synthetic lubricants which achieve enhanced oxidative stability by the practice of this invention includes the silicone lubricants. The term silicone as used in the specification and claims of this application is defined as a synthetic compound containing silicon and organic groups. In naming specific compounds, the nomenclature system recommended by the American Chemical Society Committee on Nomenclature, Spelling and Pronunciation (Chem. Eng. News, 24, 1233 (1946)) 1 7 EXAMPLE 34 Five parts of N-methyl-N-(3,S-di-tert-octyl-4-hydroxybenzyl)amine are blended with 2495 parts of diisooctyl azelate having a kinematic viscosity of 3.34 centistokes at 65 F. (ASTM 445-52T), an ASTM slope from 40 F. to 210 F. of 0.693 (ASTM D341-43) and a pour point of 85 F. (ASTM D97-47). Its flash point is 425 F. (ASTM D92-52), and its specific gravity is 0.9123 at C. The resulting lubricant is extremely stable to oxidation.

EXAMPLE Three parts of N-(2,6-diethylphenyl)-N,N-bis-(3,5- diisopropyl 4 hydroxybenzyl) amine are blended and mixed with 197 parts of a grease comprising- 12.5 percent of lithium stearate, 1 part of polybutene (12,000 molecular weight), 2 percent of calcium xylyl stearate and 84.5 percent of di-(2-ethylhexyl)sebacate, to prepare an improved grease of this invention.

EXAMPLE 36 One part of N,N-dimethyl-N-(3isopropyl-S-tert-butyl- 4-hydroxybenzyl)amine is blended with 75 parts of diisooctyl adipate having a viscosity of 35.4 SUS at 210 F., a viscosity of 57.3 SUS at 100 F., a viscosity of 3,980 SUS at F. and a viscosity of 22,500 at 65 F. Its Viscosity index is 143, its ASTM pour point is below 80 F. and its specific gravity (60 F./60 F.) is 0.926.

EXAMPLE 37 To a poly(trifluorochloroethylene) having the formula (CF CHCI) and an average molecular Weight of 880, pour point of 5 C. and a viscosity of centistokes at 160 F. is added 1.25 percent of N,N-dioctyl-N-(3-methyl- 5tert-amyl-4-hydroxybenzyl)amine to prepare an improved lubricant of this invention.

EXAMPLE 3 8 To a phenylmethyl polysiloxane fluid having a viscosity of 100-150 centistokes at 25 C., an open cup flash point of 575 F. (ASTM D92-33), a freezing point of F., and a specific gravity of 1.07 at 77 F. is added suflicient N tert-butyl-N-(3,S-di-tert-butyl-4-hydroxybenzyl) amine to give a composition containing 0.1 percent N-tertbutyl-N- 3 ,5 di-tert-butyl-4-hydroxybenzyl amine.

EXAMPLE 39 To a polyalkylene glycol oil lubricant having a viscosity index of 148, ASTM pour point of 55 F., a flash point of 300 F., a specific gravity of 0.979 and a Saybolt viscosity of 135 at 100 F. is added 1 percent of N,N- diethyl-N-(3 sec-butyl 5 tert amyl-4-hydroxybenzyl) amine, to prepare an extremely oxidation resistant polyalkylene glycol lubricant.

EXAMPLE 40 An improved lubricant of this invention comprising a chlorinated organic compound is prepared by admixing 0.5 per-cent of N,N-dipropyl-N-(3,5-di-sec-dodecyl-4-hydroxybenzyl)amine with a chlorodiphenyl oil having a distillation range of from 554 to 617 E, a Saybolt viscosity at 100 F. of about 49, a pour point of 30 F. and a specific gravity of about 1.267.

In the compositions of this invention efiective use can be made of other additives which are known to the art, such as other inhibitors, detergent dispersants, pour point depressants, viscosity index improvers, anti-foam agents, rust inhibitors, oiliness or film strength agents, dyes and the like. Of the inhibitors which can be effectively used in combination with the compounds of this invention are sulfurized sperm oil, sulfurized terpenes, sulfurized paraffin wax olefins, aromatic sulfides, alkyl phenol sulfides, licithin, neutralized dithiophosphates, phosphorus pentasulfide-terpene reaction products, diphenylamine, phenylnaphthyl amine, ,B-naphthol, pyrogallol and the like. Typical of the detergent additives that can be used in the lubricant compositions of this invention are metallic soaps of high molecular weight acids, such as aluminum naphthenates, calcium phenyl stearates, calcium alkyl salicylates, alkaline earth metal petroleum sulfonates, alkaline earth metal alkyl phenol sulfides (barium amyl phenol sulfide, calcium octyl phenol disulfide, etc.), metal salts of wax-substituted phenol derivatives and the like. Of the viscosity index improvers and pour point depressants, effective use can be made of polymers of the esters of methacrylic acids and higher fatty alcohols and the corresponding polymers of esters of acrylic acid and higher fatty alcohols. These and other additives which can be employed in the lubricant compositions of this invention will now be well known to those skilled in the art.

As noted above, the compounds of this invention are also excellent antioxidants for saturated hydrocarbon polymers.

Polyethylene and polypropylene are, for example, hydrocarbon polymers derived from the polymerization of ethylene and propylene. This polymerization can be accomplished by a great variety of methods which lead to products of diverse properties. Polymers of any nature may advantageously be utilized for preparing compositions according to the present invention. The polymers which are employed may, for example, be similar to those which may be obtained by polymerizing ethylene in a basic aqueous medium and in the presence of polymerization favoring quantities of oxygen under relatively high pressures in excess of 500 or 1,000 atmospheres at temperatures between 150 and 275 C. Or, if desired, they may be similar to the essentially linear and unbranched polymers ordinarily having greater molecular weights which may be obtained under relatively low pressures of 1 to atmospheres using such catalysts to polymerize the ethylene as mixtures of strong reducing agents and compounds of Groups IVB, VB, and VIB metals of the Periodic System; chromium oxide on silicated alumina; hexavalent molybdenum compounds; and charcoal supported nickel-cobalt. The polymer which results from these various polymerization processes may have a molecular weight in the range from 1300 to over 1,000,000 depending on the particular conditions of polymerization employed.

There are several methods available for preparing the inhibited hydrocarbon polymer compositions of this invention. Thus the blending of the additives of this invention, with a polymer such as, for example, polyethylene, may be carried out on open rolls, on internal mixers or may be accomplished by mixing with extrusion. It is also possible to prepare concentrated batches of the polymer containing excessive amounts of the additive and then mix the concentrate with additional polymer to prepare a composition of this invention. The preferred method of compounding the polymers is by milling on heated open rolls at slightly elevated temperatures by methods well-known to the art. The temperature range employed is sometimes critical as certain polyethylenes will not melt at low temperatures and tend to stick to the rolls at high temperatures. The additive may be initially mixed with the polymer in the dried state or may be first dissolved in a suitable solvent, then sprayed on the polymer and milled in.

Examples of the hydrocarbon polymers compositions of this invention prepared as described above follow. All parts and percentages are by weight in these examples.

EXAMPLE 41 To 1,000 parts of polyethylene produced by oxygen catalized reaction under a pressure of 20,000 atmospheres and having an average molecular weight of 40,000, is added and mixed 2 parts of N,N-dioctyl-N-(3,5-diisopropyl-4-hydroxybenzyl)amine. The resulting composition has a greatly increased oxidative stability.

EXAMPLE 42 To 100 parts of polyisobutylene having an average 19 molecular weight of 100,000 is added 0.5 part of N- benZyl-N,N-bis- (3 ,5 -di-tert-butyl-4-hydroxybenzyl) amine. The oxidative stability of the polymer is greatly increased by the addition of this compound.

EXAMPLE 43 To a master batch of high molecular weight polyethylene having an average molecular weight of about 1,000,000, a tensile strength of 6,700 p.s.i., a Shore D hardness of 74 and a softening temperature under low load of 150 C. is added 5 percent of N-ethyl-N,N-(3- isopropyl-5-tert-butyl-4 hydroxybenzyl) amine. Polyethylene of improved oxidative stability results.

EXAMPLE 44 A linear polyethylene having a high degree of crystallinity (up to 93 percent) and below 1 ethyl branched chain per hundred carbon atoms, a density of about 0.96 gram per milliliter and which has about 1.5 double bonds per 100 carbon atoms is treated with 5'0 10 roentgens of B-radiation. To the thus irradiated polymer is added 0.005 percent of N-dodecyl-N,N-bis-(3,5-di-tert-butyl-4- hydroxybenzyl)amine, and the resulting product has improved stability characteristics.

EXAMPLE 45 Two parts of N,N-diamyl-N-(3-tert-butyl-5-tert-amyl-4- hydroxybenzyl)amine are added with milling to 100 parts of a low density polyethylene prepared by high pressure polymerization and which has an average molecular weight of about 20,000. The resulting product is vastly improved in its oxidative stability.

EXAMPLE 46 To 1,000 parts of a solid polypropylene polymer having a density of 0.905 and a Rockwell hardness greater than 85, in which isotactic is added and blended to 5 parts of N-butyl-N,N-bis(3,5 di tert-butyl-4-hydroxybenzyl)- amine.

EXAMPLE 47 To an isotactic polypropylene having a tensile strength greater than 4300 psi. and a compressive strength of about 9,000 p.s.i. is added sufficient N-decyl-N,N-bis (3-isopropyl-S-tert-4-hydroxybenzyl) amine.

In addition to the additive of this invention saturated hydrocarbon polymers may contain other compounding and coloring additives including minor proportions of carbon black, elastomers, polyvinyl compounds, carboxylic acid esters, urea-aldehyde condensation products, flame retarding agents such as antimony trioxide and chlorinated hydrocarbons and various pigment compositions designed to impart color to the finished product.

Other hydrocarbon polymers which are stabilized against oxidative deterioration according to this invention include natural rubber, GRS and GRN rubbers, butyl rubber, methyl rubber, polybutene rubber, butadiene rubbers, piperylene rubbers, dimethylbutadiene rubbers, polystyrene, polybutadiene, polyisobutylene, polyethylene, isobutylene-styrene copolymer and, in general elastomeric hydrocarbon polymers which are normally susceptible to oxidative deterioration. Such polymers are well known in the art and besides being susceptible of oxidative deterioration are characterized by having molecular weights above about 10,000. The problem resulting from heat, light and catalyst promoted oxidative deterioration in such hydrocarbon polymers is intensified because of free radical formation within the polymers. This leads to various forms of physical and chemical degradation such as chain scission, autocatalytic oxidation, reduction in molecular weight and loss of original physical properties. The net result is that the desirable useful and necessary properties of the polymers which are associated with their original chemical structure and molecular weights are lost to a greater or lesser extent 20 unless the polymers are stabilized against such deterioration.

Typical stabilized hydrocarbon polymers of this invention are illustrated by the following specific examples wherein all parts and percentages are by Weight.

EXAMPLE 48 EXAMPLE 49 To a master batch described in Example 48 is added 0.5 percent of N-methyl-N,N-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)amine.

EXAMPLE 50 One percent of N-amyl-N,N-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)amine is added to a synthetic rubber master batch comprising 100 parts of GRS rubber having an average molecular weight of 100,000, 5 parts of zinc stearate, 50 parts of carbon black, 5 parts of road tar, 2 parts of sulfur and 1.5 parts of mercaptobenzothiazole. This batch is then cured as described in Example 48.

EXAMPLE 5 1 Two parts of N,N-dimethyl-N-[3,5-di-(1,l,3,3-tetramethylbutyl)-4-hydroxybenzyl] amine is incorporated in 100 parts of raw butyl rubber prepared by the copolymerization of percent of isobutylene and 10 percent of isoprene and having an average molecular weight of 100,000.

EXAMPLE 52 To 200 parts of raw butyl rubber having an average molecular weight of 600,000 and prepared by copolymerizing percent of isobutylene and 5 percent of butadiene is added 1.5 parts of N-methyl-N,N-bis-[3,5-di-(2- octyl) -4-hydroxybenzyl] amine.

EXAMPLE 5 3 To a master batch of GRN synthetic rubber comprising parts of GRN rubber having an average molecular weight of 75,000, 5 parts of zinc stearate, 50 parts of carbon black, 5 parts of road tar, 2 parts of sulfur and 2 parts of mercaptobenzothiazole is added 3 percent based on the weight of the batch of N,N-di-methyl-N-(3,5-ditert-butyl-4-hydroxybenzyl amine.

EXAMPLE 54 A dry blend of polystyrene and N-octyl-N,N-bis-(3 tert-butyl-S-tert-amyl-4-hydroxybenzyl)amine is prepared by mixing one part of this compound with 100 parts of polystyrene having an average molecular weight of 50,000.

EXAMPLE 55 0.25 percent by weight of N-butyl-N,N-bis-(3,5-di-tertbutyl-4-hydroxybenzyl)amine is incorporated in polybutadiene having an average molecular weight of 50,000.

EXAMPLE 56 To natural rubber (Hevea) is added 0.02 percent of N diamyl N,N-bis-(3,5-diisopropyl-4-hydroxybenzy1)- amine.

The above examples illustrate the improved composi tions of this invention. Other such compositions and the methods of preparing the same will now be apparent to one skilled in the art.

EXAMPLE 57 To illustrate the enhanced oxygen resistance Qf the hy drocarbon polymer compositions of this invention, a natural rubber compounded into a typical tire-tread formula is selected for test. One requisite of such stocks is that the desirable properties incorporated therein by careful selection of the compounding ingredients and cure time shall be maintained during extended periods of storage or use in the presence of oxygen. Comparison of various rubber stocks is best carried out on stocks initially having the same state of cure. The most reliable means for determining the state of cure is by the T-50 test, ASTM designation D-59940T, described in the ASTM Standards for 1952, Part 6. This test measures the temperature at which a test piece recovers its elasticity when it is stretched at room temperature, frozen at a sufiiciently low temperature to cause it to lose its elastic properties, and then gradually warmed. In practice the temperature noted is that at which the sample recovers to 50 percent of the original elongation and is, therefore, referred to as the T-50 value. In the examples that follow, stocks for testing and comparison were cured for a time suflicient to have a T-50 value of -45 C. so that a valid comparison of the properties could be made. The accelerated aging was conducted by the procedure of ASTM designation D-572-52, described in the ASTM Standards for 1952, Part 6, for a period of 96 hours at a temperature of 70 C., with an initial oxygen pressure in the test bomb of 300 pounds per square inch gauge on specimens having the following composition:

Parts by weight Smoked sheets 100.00 Carbon black 45.00 Zinc oxide 5.00 Stearic acid 3.00 Pine tar oil 2.00 Sulfur 3.00 Mercaptobenzothiazole 0.65

To demonstrate the protection afforded to the rubber by the inhibitors of our invention, the tensile strength and the ultimate elongation of stocks prepared by the addition of an inhibitor of this invention is determined before and after aging. These properties are compared with the same properties determined on an identical rubber stock not protected by an inhibitor. Both of these properties are determined by means of the test procedure of ASTM designation D-41 2-51T, fully described in ASTM Standards for 1952, Part 6. The tensile strength is the tension load per unit cross-sectional area required to break a test specimen, while the ultimate elongation is the elongation at the moment of rupture of a test specimen. A decrease in the values for either of these properties upon aging represents a decrease in the usefulness of the article fabricated therefrom, so that the degree to which these proper-ties are retained is a direct measure of the utility of the protective substance.

EXAMPLE 5 8 The inhibitors of this invention find particular utility in the stabilization of light colored hydrocarbon polymers where non-staining characteristics of the inhibitor are essential. To illustrate the non-staining characteristics of the above described phenolic inhibitors in the protection of light colored stocks the following base formula is used.

Parts by weight Pale crepe rubber 100.00 Zinc oxide filler 50.00 Titanium dioxide 25.00 Stearic acid 2.00 Ultramarine blue 0:10 Sulfur 3.00 Mercaptobenzothiazole 1.00

To the above base formula is added one part by weight of N,N-dimethyl-N-( 3,5 -di-tert-butyl-4-hydroxybetnzyl) amine and the sample is cured for 45 minutes at 274 F. using perfectly clean molds with no mold lubricant. After curing, a sample of the above protected light colored stock is exposed for 24 hours using a discoloration weatherometer so as to determine the amount of discoloration which occurred during this period of time. It is found that the presence of the additive of this invention in this light colored stock causes essentially no discoloration.

Another cured sample of the above light colored stock containing the additive is subjected to a test procedure designed to determine the amount of migration staining. In this test, a piece of the above cured sample is placed between two steel panels which had been painted with enamel and allowed to dry, This sample is then exposed for 48 hours at 212 F. in a hot air oven using a 5 pound weight on the panels to maintain rubber-to-metal contact. On completion of this test it is found that essentially no migration staining had occurred.

The amount of inhibitors of this invention employed in hydrocarbon polymers varies from about 0.01 to about 3 percent by weight of the polymer stabilized depending upon the nature of the polymer and the conditions of service to be encountered. Thus in the stabilization of natural and synthetic rubber to be used in the manufacture of tires which are normally subjected to exposure to the elements as well as to the action of sunlight, frictional heat, stress and the like, the use of relatively high concentrations of our inhibitors is advantageous. On the other hand, when the article of manufacture is not to be subjected to such severe conditions, such as in the case of molded goods fabricated from polyethylene, relatively low concentrations of my inhibitor can be successfully utilized.

As noted above the stabilizers of this invention are also excellent additives to tetraalkyllead antiknock compositions. The tetraalkyllead antiknock agents which are stabilized according to this invention are represented by such compounds as tetramethyllead, tetraethyllead, tetrapropyllead, dimethyldiethyllead, trimethylethyllead, and the like, or mixtures thereof. Such compounds containing from 4 to about 12 carbon atoms, one atom of lead and a plurality of lead-t-o-carbon bonds, are capable of increasing the octane quality of gasoline when employed therein in antiknock quantities0. 5 to 6.5 grams of lead per gallon. Halogen-confining compounds such as triethyllead bromide may also be stabilized according to this invention.

The scavengers which are preferably, but not necessarily, present in the antiknock compositions of this invention are organic halide compounds which react with the lead during combustion in the engine to form volatile lead halide. The halogen of these scavengers has an atomic weight between 35 and that is, the active scavenging ingredient is chlorine and/or bromine. Such scavengers include carbon tetrachloride, propylene dibromide, 2-chloro-2,3-dibromobutane, 1,2,3-tribromopropane, hexachloropropylene, mixed bromoxylenes, 1,4-dibromobutane, 1,4 dichl-oropentane, 6,6 dibrornodiisopropyl ether, fl,5-dichlorodiethyl ether, trichlorobenzene, dibromotoluenes, and in general those disclosed in US. Patents 1,592,954; 1,668,022; 2,364,921; 2,479,900; 2,479,901; 2,479,902; 2,479,903; and 2,496,983. In short, I prefer to employ scavengers containing only elements selected from the group consisting of carbon, hydrogen, bromine, chlorine and oxygen, The amount of scavenger used is from about 0.5 to about 2.0 theories, a theory being defined as the quantity required to react with the lead to form lead halide-i.e. 2 atoms of halogen per atom of lead. When we used mixtures of brominecontaining and chlorine-containing scavengers, particularly bromo and chlorohydrocarbons, I can employ concentrations and proportions as described in US. Patent 2,398,281. Such concentrations are sufficient to control the amount of deposits formed in the engine.

Representative tetraalkyllead antiknock compositions of this invention are presented in Table IV following. The figures following the representative ingredients are parts by weight. The two figures following the stabilizing ingredient show respectively the amounts which are used to obtain a composition containing 0.1 and 1.0 percent by weight of stabilizer based on the lead alkyl antiknock agent. It will be apparent that if the lower figure is halved, the resulting composition will contain 0.005 percent by weight of the stabilizing ingredient based on the lead alkyl, whereas doubling the second figure will provide a composition containing 2.0 percent. Should other concentrations be desired, the proper adjustments are evident.

animal fats and oils, especially lard, against the effects of rancidity. The compounds of this invention may be used in concentration from 0.001 to about 0.1 weight per cent in this embodiment of the invention. In addition, an acid synergist may be employed to promote the activity of the additives of this invention. These synergists which mutually cooperate with the compounds of this invention to produce a disproportionately large increase in effectiveness in stabilizing fatty materials including citric acid, phosphoric acid, abscorbic acid, ethyl acid phosphate, gl-ucuronolactone, phytic acid, tartaric acid and aconitric acid.

In formulating the stabilized non-petroleum fats and oils of this invention, the additive or combination of additives is incorporated by appropriate means into the substrate to be stabilized. Thus, in the case of animal,

Antiknock Agent Scavenger Stabilizer Tetramethyllead 2G7 Ethylene dibromide 94 and ethylene dichloride N,N-dimethyl-N-(3,5-diisopropyl-4-l1ydroxybenzyDarnine, 0.27-2.67. N-propyl-N,N-bis(3,5-di-tert-amylA-hydroxybenzyDamine, 0.32-3 23 Tetraethyllead 323 None Tetraethyllead 323 Ethylene dibromide 188 Tetraethyllead 323 Ethylene dibromide 94 and ethylene dichloride Tetrapropylload 379 A tylene tetrabromide 346 Dimethyldiethyllead 295 B,r3dibromodiethyl ether 232 Methyltriethyllead 309 flfldibromodiisopropyl ether 130 and fl,fl-di- N,N-dirnethyl-N-(3,5-ditert-butyl-4-hydr0xybenzyDamine, 0.32-3.23. N,N-diInethyl-N-(3,5-di-tert-butyl-4-hydroxybenZyDamine, 0.32-3.23. N-benzyl-N-(3-methyl- -tert-octyl-4-hydroxybenzybamine, 0.38-3.79. N-(2,6-diethylphenyl)N,N-bis(3,5-di-tert-butyl- 4-hydroxybenzyl)amine, 0.302.95. N-methyl-N-(3,5-di-tert-butyl-4-hydroxychloro-diethyl ether 143.

benzyDamine, 0.31-3.09.

The antiknock fluid compositions shown in the above table are presented for illustrative purposes only. Other such compositions will be apparent to one skilled in the art. In all instances, the presence of the compound of this invention enhances the stability characteristics of the formulation over those prevailing in the absence of my stabilizer.

The tetraalkyllead antiknock compositions of this invention may contain other ingredients such as dyes for identification purposes, metal deactivators, diluents and the like.

Antiknock compositions containing tetraalkyllead antiknock agents are employed by adding them to gasoline to improve the antiknock quality thereof. Such gasolines both before and after addition of the antiknock fluid are benefited by the practice of this invention. Thus gasolines to which have been added a compound of this invention are found to be more stable upon prolonged periods of storage.

The following examples illustrate gasoline embodiments of this invention.

EXAMPLE 59 To 10,000 parts of a grade 115/145 aviation gasoline containing 4.5 ml. of tetraethyllead per gallon which has an initial boiling point of 110 F. and a final boiling point of 330 F. and an API gravity of 71.0" is added .5 percent of N,N-dimethyl-N-(3,5-di-tert-bu-tyl-4-hydroxybenzyl) amine.

EXAMPLE 60 To a gasoline containing 26.6 percent aromatics, 20.8 percent olefins and 52.6 percent saturates and which has an API gravity of 62.1 is added 0.1 percent of N-metl1yl- N, N-bis-: 3 ,5 -diisopro pyl-4-hydroxybenzyl) amine.

Similarly, other compounds of this invention may be added with benefit to gasoline of whatever nature and however processed.

As noted above the compounds of this invention are also extremely useful in inhibiting and stabilizing nonpetroleum fats and oils normally subject to the deteriorating effect of ox-idative rancidity. In particular, compounds of this invention are excellent stabilizers for vegetable and fish oils, the additive of combination of additives is added in appropriate quantity and the result ing mixture agitated to insure homogeneity. Where the substrate is a solid at room temperaturese.g., fats, butter, etc.the mixing is preferably carried out at temperatures above the melting point of the substrate. When a combination of additives is used, they can be mixed with the substrate as a preformed mixture or can be separately blended therewith in either order. Generally speaking, it is desirable to first dissolve the additive or additive combination in high concentraton in a small portion of the material to be stabilized. The resulting concentrated solution then blended with the remaining bulk. Another way of facilitating the formulation of the composition of this invention is to pre-dissolve the additive or combination of additives in a suitable solvent, such as ethanol, glycerol, propylene glycol, etc. and then mix the resultant solution with the material to be stabilized. However, the preferred way of formulating the compositions of this invention is to pre-dissolve the additive or additive mixture in a fatty acid partial ester of a polyhydroxy compound, notably a monoglyceride, and then blend this mixture with the material to be stabilized. The nature of these monoglycen'de compositions is well known in the art and may be made from either animal or vegetable fats, with or without previous hydrogenation. These compositions generally contain about 40 percent of the monostearyl, monooleayl, and/or monopalmityl glycerides or mixtures thereof with the balance comprising a mixture of diand triglycerides. Molecularly distilled monoglycerides may also be used for this purpose. These compositions will be apparent from the following examples.

EXAMPLE 61 With 1,000 parts of melted lard is mixed one part (0.1 percent) of N,N-dimethyl-N(3,5-di-teIt-butyl-4-hydroxybenzyl)amine. After cooling the lard can be stored for long periods of time without the development of rancidity.

EXAMPLE 62 With 5,000 parts of cotton seed shortening is blended 25 0.05 part (0.001 percent) of N-octyl-N,N-bis-(3-isopropyl--tert-buty1-4-hydroxybenzyl)amine. The resulting shortening has improved resistance against oxidative rancidity.

EXAMPLE 63 In 2.5 parts of propylene glycol is dissolved with stirring one part of N-methyl-N,N-bis-(3,5-di-tert-butyl-4- hydroxybenzyl)amine. The resulting mixture is then added with stirring to 10,000 parts of cod liver oil. The resultant oil containing 0.01 percent of the additive possesses increased resistance against oxidative deterioration.

EXAMPLE 64 To 10,000 parts of corn oil are added with stirring 5 parts (0.05 percent) of N,N-diamyl-N(3,5-di-tert-amyl- 4-hydroxybenzyl)amine and 2 parts (0.02 percent) of abscorbic acid. The resulting corn oil has improved storage stability characteristics.

EXAMPLE 65 To 100 parts of monoglyceride (prepared from a partially hydrogenated vegetable oil) heated to 180 F. is

added with stirring 5 parts of N,Ndimethyl-N-(3,5-ditert-butyl-4-hydroxybenzyl)amine and 4 parts of citric acid. Ten parts of the resultant monoglyceride formulation are added with stirring to 10,000 parts of melted prime steam lard. The lard composition so formed which contains 0.005 percent of the amine and 0.004 percent of citric acid can be stored at room temperature for long periods of time without developing rancidity.

Those skilled in the art will now clearly understand the various methods of preparing the improved compositions of this invention.

This application is a continuation-in-part of application Serial No. 536,316, filed September 23, 1955, now US Patent No. 2,962,531, and application Serial No. 6,334, filed December 28, 1959.

I claim:

1. Organic material normally tending to undergo oxidative deterioration in the presence of air, oxygen or ozone containing a small antioxidant quantity, up to 3 percent, of a 3,5-dialkyl-4-hydroxybenzyl amine having the formula 1 R1 HO- CHzN J R2 2-:

wherein R is alkyl of from 1-12 carbon atoms; R is an alkyl of from 3-12 carbon atoms characterized by being branched on the alpha carbon atom; R is selected from the group consisting of alkyl of 1-12 carbon atoms, cycloalkyl of 5-6 carbon atoms, hydrocarbon aralkyl of 7-11 carbon atoms, hydrocarbon aryl of 6-10 carbon atoms and hydrocarbon alkaryl of 7-12 carbon atoms; R is selected from the group consisting of hydrogen and R and x is 0 or 1, said organic material being selected from the class consisting of gasoline, petroleum wax, high molecular weight unsaturated polymers, solid saturated hydrocarbon synthetic polymer derived from the polymerization of an olefinically unsaturated monomer having from 2 to 4 carbon atoms, edible fats and oils of animal and vegetable origin, tetraalkyllead antiknock agents, diester oils, fluorocarbon oils, polyethylene glycol oils, silicone oils and phosphate oils.

2. The composition of claim 1 wherein said organic material is a high molecular weight unsaturated polymer.

3. The composition of claim 1 wherein said high molecular weight unsaturated polymer is rubber.

4. The composition of claim 6 wherein said amine is a 3,S-di-tert-alkyl-4-hydroxybenzyl amine.

5. The composition of claim 4 wherein said 3,5-di-te1talkyl-4-hydroxybenzyl amine is N,Ndimethyl-N-(3,5-ditert-b utyl-4-hydroxybenzyl) amine.

6. The composition of claim 3 wherein R and R are alkyls of 1-12 carbon atoms.

7. The composition of claim 1 wherein said organic material is a grease which comprises a hydrocarbon oil thickened by means of a soap.

8. The composition of claim 7 wherein R and R are alkyl radical of 1-12 carbon atoms.

9. The composition of claim 8 wherein said amine is a 3,5-di-tert-alkyl-4-hydroxybenzyl amine.

10. The composition of claim 9 wherein said 3,5-di-tertalkyl-4-hydroxybenzyl amine is N,N-di-methyl-N(3,5-ditert-butyl-4-hydroxybenzyl) amine.

11. The composition of claim 1 wherein said organic material is gasoline.

12. The composition of claim 1 wherein said organic material is a solid saturated hydrocarbon synthetic polymer derived from the polymerization of an olefinically unsaturated monomer having from 2 to 4 carbon atoms.

13. The composition of claim 1 wherein said organic material is edible fats and oils of animal and vegetable origin.

14. The composition of claim 1 wherein said organic material is a tetraalkyllead antiknock agent.

References Cited by the Examiner UNITED STATES PATENTS 2,802,810 8/57 Bill 26045.7 2,928,790 3/ Bartleson 252-400 2,962,531 11/60 Coflield 260--570.9

LEON I. BERCOVITZ, Primary Examiner.

A. M. BOETTCHER, ALPHONSO D. SULLIVAN,

MILTON STERMAN, DONALD E. CZAIA,

Examiners. 

1. ORGANIC MATERIAL NORMALLY TENDING TO UNDERGO OXIDATIVE DETERIORATION IN THE PRESENCE OF AIR, OXYGEN OR OZONE CONTAINING A SMALL ANTIOXIDANT QUANTITY, UP TO 3 PERCENT, OF A 3, 5-DIALKYL-4-HYDROXYBENZYL AMINE HAVING THE FORMULA 